Signaling system



March 30, 1943. J E. sTLINE SIGNALING SYSTEM `Filed Aug. 2, 1941 3 Sheets-Shea?l l R w 0 m .w E m Wd \N\m Q E @m50 .WW NMF@ Sm, m \.Q\\\ Y @E @Q JQ@ m@ p @www @Q E m Q Af 5m, l A 1v. S QQJ MNE @L MQ@ Q wasn WC/m@ 6% @NB QH @NEEN 4 EW Jv. L o QS. p @www lAl NQ Tl- NQS T55 www @QH @uhmm man wb@ RSN oli @QB Al ES@ N @QN MQQNUmNm@ March 30, 1943.

J. E. OSTLINE SIGNALING SYSTEM 3 Sheets-She'et 2 Filed Aug. 2, 1941 March 3o, 1943. J E. OSTUNE 2,315,010

SIGNALING SYSTEM Filed Aug. 2, 1941 3 Sheets-Sheet 5 f 6 35554 @mag 310 F9 3 i 5 if V, 7,1-, INVENTOR ATTOR N EYS Patented Mar. 30, 1943 UNITED SIGNALING SYS TEMZ John Ellis Ostline, Chicago, Ill.assigrior.tcAsso ciated Electric Laboratories,p1i 1 c Chicago, Ill., a corporation of DelawareY Application August 2, 1ML-Serial No. 405,155;V

1S Claims.

The present invention relates to signaling systemsand more particularly to improved switching apparatus for automatic telephone systems.

An automatic telephone system conventionally comprises: switching apparatus including aselector having access toten groups of trunks respectively terminated in the ten levels in the associated terminal bank. Also, a selector of thischaracter may be rendered access to a larger number of 'trunk groups by splitting oneor more levels in the associatedlterminal bank, whereby each: of the splitlevels 4terminates two separate type mentioned, which is of simple construction.

and connection and which is economical to manufacture and thoroughly reliable in operation.

Another object of the invention is to provide an improved selector ofv the split level type, which comprises aV single access trunk anda Wiper set including a single test wiper.

Afurther object of the invention is to provide a telephone system comprising improved switching apparatus for setting up connections between the various subscriber substations and between the subscriber substations and the service operator positions, in a simple and efcient manner.

A further and more specic object of the invention is to provide an improved selectorv of the split level type, which comprises a simple and reliable mechanism for selectively controlling the operation thereof to select idleftrunks in the two groups terminated in each split level in the associated terminal bank.

Further features of the invention pertain to the particular arrangement of the mechanical elements of the selector and of the circuit elements of the telephone system, whereby the above-outlined and additional operating features are attained.

'Ihe novel features believed to becharacteristc of the invention are set forth with particularity in` the appendedl claims. The. invention, both as to its organization: andmetliod of operation, together with .further objectsand advantagesthereof; willifbest; be understoodV ,by ref erence -to the following, specification taken in connection with the accompanying drawings, in, whichFigs. 1 and 2taken,together` illustrate diagrammatically a Vtelephone system embodying the present. invention; Eig. r3.- is` airagmentary plan. `viewgof Y aportion of the switching, mecha,-

nism incorporatedA in a selector embodying. the

present invention; Eig. 4isa fragmentary side e-levationaltview.. of; lthe portion ofl the.v switching mechanism. showninlig, 3; Fig. 5v is a, further iragmentaryf side elevational View of the portion of the.. switching; mechanismy mentioned; and i Fig. 6 illustrates diagrammatically aswitchk spring.. assembly.. incorporated; inthe switclfiing` mechanism.

Referringinow. more particularly to4 Figs. land.

2.1offthe drawinga: there'` is shownra telephone system, including an. exchange serving a pluralityofj'subscriber substations Ti, T2; etc., andv including. switching.- apparatus and operator p csition 1 equipment: Moret particularly, offsubscri-benlines I fl, 2530; etc., respectively, ex-

. tend toV the-subscriber, substationsTl, T2; etc.,

and terminateA in theswi-tching,apparatus at the exchange. More.` speci-cally, each subscriber line terminates .inaline switch individual thereto .included in f the switching apparatus, the subscriber. linesl lill andf230 respectively terminatingc-in theline switches 102;; and. 21H. The operator position. equipment. provided in the` eX.- change l comprises a manual operator position li, atoll operator position-.12ML` an information'op.-

a erator position l|32and a` miscellaneous operator position H2.

The..switchingapparatusV provided at the exchange-comprises, infadditionto the line switches |02', 231., etc., aplurality of selectors l, etc., a

group. oirspecialservice selectors 233, etc.,'and ten.. groups of connectors, the connector 2321beingincluded-in thetenthlgroup.

Eachoff the subscribersubstations Tl, etc., comprises conventional substation equipment including a telephoneinstrument, a ringer,V and a callingdevice; while eachof the operator positions H0; etc., is provided with conventional operatorposition-I equipment- Each of the line switches |02; etc.-,visoficonventional connection and arrangement- Also, each of the special serviceselectors 233, dropeback-Strowger type; while each of they connectors 2.32', etc., isofithe conventional Strowger typei Finally, the various.l trunks extending to thedilerent operatorv positions 0, H0; etc.,` are a plurality.`

etc., is of the conventionalprovided with conventional trunk circuits, not shown.

Preferably, each of the selectors is identical to the selector 100 which comprises a switching mechanism 110, a relay group including a switchthrough relay R110, a line relay R120, a hold relay R130, a transfer relay R140, a step relay R150 and a prefix relay R160, and a control network. The switching mechanism 110 is of the drop-back Strowger type, including a wiper shaft 11| carrying three wipers 112, |13 and 114, and an associated semicylindrical contact bank 115. The contact bank 115 comprises ten.vertical levels of Contact sets, each level of contact sets including ten circumferentially spacedapart individual contact sets. Also, the switching mechanism 110 comprises a vertical magnet M116 for driving the wiper shaft |11 in the vertical direction, a rotary magnet M111 for driving the wiper shaft 111 in the rotary direction, and a release magnet M113 for releasing the wiper shaft ,11| and for causing it to be returned Ato its normal rotary and vertical positions.

Two sets of switch springs S180 and S181 are associated with the wiper shaft 111 and controlled by the movement thereof away from its normal vertical position; three sets of switch springs S188, S191 and S194 are associated with the wiper shaft 111 and controlled by the movement thereof away from` its normal rotary position eleven steps inthe rotary direction; two sets of switch springs S182 and S1183 are associated with the wiper shaft y11| and controlled by the movement thereof away from its normal vertical position a predetermined number of steps in the vertical direction; and one set. of switch springs S184 is associated with the wiper shaft 111 and controlled by the movement thereof away from its normal rotary position a predetermined number of steps in the rotary direcwhile the last three contact sets in the tenth level in the contact bank 115 individually terminate three trunks 208, etc., respectively extending to the manual operator position 0. Finally, the ten contact sets in each of the levels from the second through the ninth levels in the contact bank 115 individually terminate ten trunks respectively extending to ten connectors included in the groups from the second to the ninth, inelusive.

Referring now more particularly to Figs. 3 to 6, inclusive, of the drawings, there is shown in tion only when the wiper shaft 111 has been previously moved in the vertical direction predetermined numbers of steps and corresponding to certain levels of the associated contact bank 115, as explained more fully hereinafter.

Considering now the trunking arrangement of the telephone system, it is noted that the line switch 102 individually associated with the subscriber line 101 has access to a number of trunks 105, etc., individually extending to the selectors 100, etc.; the connector` 232 included in the tenth group has access to one hundred subscriber lines including the subscriber line230; and the special service selector 233 has access to three groups of trunks respectively including the trunks 234, 235 and 236 vrespectively extending to the toll operator position 1 10, the information operator position 113 and the: miscellaneous operator position 1 112'.r The first five contact sets in the first level in the contact bank 115 of the switching mechanism |10 incorporated in the selector 100 individually terminate five trunks 2|1, etc., respectively extending to five connectors included in the first group; while the last five contact sets in the rst level in the contact bank 115 individually terminate ve trunks 216, etc., respectively extending to five special service selectors, the trunk 216 extending to the special service selector 233. Also, the first seven contact sets in the tenth level in the contact bank 115 individually terminate seven trunks 20|, etc., respectively extending to seven connectors included in the tenth group, the trunk 201 extending to the connector 232 in the group mentioned;

`greater detail a portion of the switching mechanism incorporated in the selector 100. This portion of the switching mechanism 110 comprises the wiper shaft 111 previously mentioned, the wiper shaft 111 being mounted in suitable bearings, not shown, for both step-by-step movement in the vertical direction and step-by-step movement in the rotary direction. Also, the wiper shaft 111 carries a vertical ratchet 301 which cooperates with a drive pawl, not shown, which is driven by the vertical magnet M116, and a rotary ratchet 302 which cooperates with a drive pawl, not shown, which is driven by the rotary magnet M111. Also, a vertical retaining pawl, not shown, cooperates with the vertical ratchet 301 and a rotary retaining pawl, not shown, cooperates with the rotary ratchet 302, the last-mentioned pawls being-operatively asscciated with the release magnet M119. Further, this portion of the switching mechanism 110 comprises a switch spring assembly, including first and second sections, the rstsection of the switch spring assembly including the switch` springs 185, 186 and 181 and the second section of the switch spring assembly including the switch springs 189, 190, 192, 193, 195, 196 and 191.

Further, the wiper shaft 111 carries a substantially U-shaped bracket 303 provided with two.

spaced-apart arms 304 and 305, the wiper shaft |11 extending through aligned holes provided in the arms 304 and 305. The bracket 303 is retained in place on the wiper shaft 111 by two screws 306 and 301 respectively arranged in tapped holes provided in the arms 304 and 305, the ends of the screws 306 and 301 engaging the cylindrical outer surface of the wiper shaft 111. Finally, the wiper shaft 111 carries one or more slotted cams 310, two cams 310 being illustrated. Each of the cams 3|0 has an elongated slot 311 formed therein, which extends from the center to the periphery thereof. The cams 310 are disposed between vthe arms 304 and 305 of the bracket 303, the slot 311 provided in each of the cams 310 straddling the wiper shaft 111. Each of the cams 310 is retained or clamped in place upon cam 310 disposed on the opposite sides of the slot,

31 1 may be forced toward each other Vby the screw 312 into gripping relation with the outer cylindrical surface of the wiper shaft 11|. This gripping action of the body portions of the cam 310 disposed on the opposite sides of the wiper shaft |11 is facilitated by a narrow slit 313 formed in the body portion of the cam 310 in alignment with the slot 31 1.

rEhe bracket 333" and`the various-earns` SIU" carried v*by the wiper shaft |1I are disposed adjacent the switch spring assembly and cooperate with a roller Sill carried on the outer end of the switch'spring` |85. More particularly, the roller SHI is arranged between two inwardly disposed and spaced-apart arms SI54 carried on the outer end ofthe switch spring |86 and mounted upon a pin SI extending between the arms SI5. Each of the cams SH! comprises a first cylindrical cam surface SI1 of a relatively small radius disposed in noncooperating relationship with respect to theroller 3 i5, and a second cylindrical cam surface SIS of a relatively large radius disposed in cooperating relationship with respect to the roller Shi; while the leading edge of the bracket 3D3 is provided with a cylindrical cam surface SIS arranged exteriorly of the second cam surface BIS of the cam 3 I 3 and disposed in cooperating relationship with respect to the roller 3 I 4.

Finally, the outer surface of the portion of the wiper shaft Ill disposed between the arms 35M and Seb of the bracket 3533 carries indicia in the form of the numerals l to G, inclusive, which is utilized for reference purpose in locating the vertical positions of the various cams SID carried by the wiper shaftl 'il with respect to the vertical steps thereof, as explained more fully below. Similarly, the upper surface of each of the cams SIG carries indicia in the form of the numerals l to O, inclusive, which is utilized for reference purpose in locating the rotary position of the cam carried by the wiper shaft I1! with respect to the rotary steps thereof, as explained more fully below. In the present example, two cams SIQ'are carried by the portion of the wiper shaft i'II disposed between the arms Sil@ and 3M of the bracket 3133; the upper cam SID being positioned adjacent the numeral l of the indicia mentioned and cooperating with the roller 3M `in the first vertical step of the wiper shaft |15, and the lower cam 3|@ being positioned adjacent the numeral of the indicia mentioned and cooperating with the roller Shi in the tenth vertical step of the wiper shaft I'II.

When the wiper shaft I'Il occupies both its normal vertical and rotary positions the upper cam 3|@ is disposed one step below the roller 3M; and the first cam portion SI1 of each cam 3||| is disposed in radial alignment with respect to the roller Sie. Accordingly, when the wiper shaft I1I is moved step by step in the vertical direction the upper cam 3|@ is brought into the plane of the roller Shi upon the iirst vertical step and the lower cam 3H) is brought into the plane of the roller 3i@ upon the tenth vertical step. Subsequently, when the wiper shaft |1| is moved step by step in the rotary clockwise direction the upper cam BIE] or the lower cam Sill, respectively, cooperates with the roller 3M only in the event the wiper shaft |1| respectively occupies its first or tenth vertical step at this time. Assuming that the wiper shaft |1| has been previously driven one step in the vertical direction when the step- Icy-step movement in the rotary clockwise direction thereof is initiated, the seco-nd cam surface 3|8 of the upper cam 3I will engage the roller BIG upon some rotary step, depending upon the adjusted position of the upper cam 3H] with respect to the wiper shaft I'EI. It will be apparent that by shifting the rotary position of the upper cam 3 i il with respect to the wiper shaft |1 I, as indicated by the position of the indicia mentioned with respect to the leading edge of the cam surface SEQ provided on the bracketSJS, the

be adjusted*v to engage thel roller B14-at.` any1 ro, tary'step; In the illustrated example,the:nu meraly1-of Ythe indicia vmentioned,"carried-l by the upper surface of the upper camv Sie; is arranged? in'alignment with the leading'edge'of the; cam surface3|9 of the bracket 393 due tothe adjust:

mentiof the upper cam 3|0 with respecttorthe;

wiperfshaft |1I; accordingly, in the illustrated example, when thewiper shaft |1| 'is drivenl one step in the rotary clockwise directionY they second cam .surface SIS of the upper cam '.iizengages the roller 3 I4.

When vthe roller 3I4'is thus engaged'bythe second cam surface 3|8 -of the uppercam-.13H1` clockwise direction, and regardless of the veroperated in order to govern the switch springs incorporated in the selector |60, as well as the tical stepped position thereof, the cam surface 3| 9 of the bracket 3%3 engages the roller 3M. When the roller 3|@ is thus engaged by the cam surface 3|9 of the bracket 363 the movable switch spring IS is moved out of engagement with the stationary switch spring |35 and into engagement with the stationary switch spring |81, in the eventthis operation has not previously occurred. Further, at this time, the movable switch springgl engages an insulator 32%) carried by the switch springs IES, ISZand |95. When the insulator 329 is thus engaged the switch springs |89, ISB and |92, |93 are respectively moved into disengagement; then the switch springs |95 and |95 are moved into engagement; and, nally, the switch springs |96 and |951 'are moved into disengagement, as clearly shown in Fig. 6.

In View of the foregoing explanation of the mode of operation ofthe porti-on of the switching mechanism |10 shown in Figs. 3 to 6, inclusive, of ,the drawings, it will be understood that, by appropriately adjusting both the vertical and rotary positions of one or more cams 3H] carried by the wiper shaft |1|, the roller 3H! may be |85, |86 and |81 at one or more variable operated positions of the switching mechanism I'IIJ, each variable operated position of the switching mechanism comprising any predetermined vertical step and any predetermined rotary step of the wiper shaft I1I which may be desired. Further, it will be understood that in the switching mechanism |19 the roller 3M will be operated -v`by the bracket 303 when the wiper shaft I1I is moved eleven steps away from its normal rotary position, regardless of the previous vertically stepped position of the wiper shaft I1I away from its normal vertical position.

The operation of the switching mechanism |10 general connection and arrangement of the system, will best be understood from a consideration of the yfollowing description, with reference to Figs. 1 and 2 of thedrawings, of the operation of the apparatus incorporated therein to set up the different connections between the various subscriber substations and betweena subscriber substation and the various operator positions.

Considering now the extension of a call from asubscriber substation, such, for example, as the subscribersubstation TI connected to the subscriber line IUI to another subscriber substation, such, for example, as the subscriber substation T2 connected to the subscriber line 230, the call'7 secondcam surface-3281er .the upper came tomar is rst initiated at the calling subscriber substation TI by removing the receiver of the telephone instrument thereat from its associatedv trunk extending to an idle selector in the asso-4 ciated group. Assuming that the selector is the first idle selector in the group accessible to the line switch |02, the line switch mentioned operates to seize the trunk |05, the trunk individually extending to the selector |00 and being marked as idle by the absence of ground potential upon the control conductor C|08 thereof.

When the trunk |05 is thus seized by the line switch |02 a loop circuit is completed between the line relay R|20 in the selector |00 andA the calling subscriber substation TI. This loop circuit extends from ground by way of the switch springs |97 and |95 of the set of switch springs SL94, the lower winding of R| and the contacts |3 to the line conductor C|0`| of the trunk |05, and from battery by way of the upper winding of R|20 and the contacts l|i to the line conductor C|06 of the trunk |05, the line conductors C|06 and C|0'| of the trunk |05 being connected by way of the line switch |02 and the line conductors of the subscriber line i0| to the calling subscriber substation Tl. When this loop circuit is completed the upper and lower windings of the line relay R|20 are energized, thereby to cause the latter relay t0 operate. Upon operating, the line relay R|20 completes, at the .contacts |2|, an obvious circuit, including the contacts for energizing the winding of the hold relay Rl30, thereby to cause the latter relay to openate. Upon operating, the hold relay R| completes, at the contacts |3 l, an obvious path for applying ground potential to the control conductor C|08 of the trunk |05 in order to retain the line switch |02 in itsv operated position and to mark the subscriber line |0| extending to the calling subscriber substation TI as busy to the connectors having access thereto.

At this time, the subscriber at the calling subscriber substation Tl dials the directory number of the called subscriber substation T2 which, in the present example, is 2OXX, this number comprising the prex digit 2, the digit 0 identifying the group of connectors, including the connector 232, having access to the subscriber line 230 extending to the called subscriber substation T2, and the digits XX identifying the vertical and rotary positions of the contact set terminating the subscriber line 230 appearing before the Various connectors in the group mentioned. The line relay R|2 follows the impulses of the prefix digit 2, resto-ring each time the loop circuit mentioned is interrupted and operating each time the loop circuit mentioned is recompleted. Each time the line relay R|20 restores it completes, at the contacts |22, a circuit, including the contacts ||1 and |33, for energizing in series the winding of the transfer relay R| and the vertical magnet M| 16, and interrupts, at the contacts 2 the previously traced circuit for energizing the winding of the hold relay R|30. Each time the line relay R|20 operates it completes, at the contacts |2|, the previously traced circuit for energizing the winding o-f the hold relay Rl30, and interrupts, at the contacts |22, the previously traced circuit for energizing in series the winding of the transfer relay R|40 and the vertical magnet MHG. When the transfer relay R|40 is thus energized the Yline it operates; and each time the vertical magnet MHS is thus energized it operates in order to drive theV wiper shaft of the switching mechanism |10 one step in the Vertical direction. Both the .hold relay R|30 and the transfer relay R|40 are of the slow-to-release type. Accordingly,

these relays remain operated during impulsing.

When the wiper shaft Ill of the switching mechanism |10 is driven one step in the vertical direction the set of switch springs S| is actuated into engagement, thereby to prepare a circuit traced hereinafter for energizing the winding of the step relay R|50; and the set of switch springs S 8| is actuated into engagement, thereby to prepare a circuit traced hereinafter for energizing the release magnet M|'|9. Upon operating, the transfer relay R|40 completes, at the contacts 4|, the previously mentioned circuit for energizing the winding of the step relay R150, this circuit extending from ground by way of the contacts |3| and |4|, the sets of switch springs S|80 and S|03 and the winding of R|50 to battery. When thus energized the step relay R|50 operates to prepare, at the contacts 5|, a circuit traced hereinafter for energizing the 'rotary magnet Ml Ti. Also, the step relay Ri 50 completes', at the contacts |52, a path for short-circuiting the winding of the switch-through relay RI 0, thereby positively to prevent operation of the latter relay at this time. rli'he path mentioned extends from ground by way of the contacts and |52, the winding of R! I0, the switch springs |00 and |89 of the set of switch springs Sl, the control conductor C|08 of the trunk |05 and the contacts |3| to ground.

-In the present example, at the conclusion of the prefix digit 2, the wiper shaft Ill occupies its second vertical step, whereupon the set of switch springs SI83 is actuated into disengagement and the set of switch springs S|82 is actuated into engagement, the sets of switch springs S|82 and S|83 being actuated in the manner mentioned only when the wiper shaft l'll of the switching mechanism |10 is driven two steps in the vertical direction. When the set of switch springs S|83 is thus actuated into disengagement the previously traced circuit for energizing the winding of the step relay R50 is interrupted, thereby to cause the latter relay to restore. Upon restoring, the step relay R|50 interrupts, at the contacts |5|, a point in the previously mentioned prepared circuit for energizing the rotary magnet MITI, and interrupts, at the contacts |52, the previously traced path for short-circuiting the winding of the switch-through relay RI I0. When the set of switch springs S|82 is actuated into engagement a circuit traced hereinafter is prepared for energizing the release magnet MI 19.

At the conclusion of the prex digit 2, the line relay R,|20 retains its operated position, thereby to retain operated the hold relay RISU; and shortly thereafter the transfer relay RI40 restores, the latter relay being of the slow-to- .release type, as previously noted. Upon restoring, the transfer relay R|40 interrupts, at the contacts |4I, a further point in the previously traced circuit for energizing the Winding of the step relay R|50, and completes, at the contacts |42, the previously mentioned circuit for energizing the release magnet MHS. The last-mentioned circuit extends from ground by way of the contacts |3| and |42, the set of switch springs S|82, the contacts |68 and the release magnet M|l9 to battery. When thus energized the release magnet MIIS operates to release the switching mechanism 1111,. thereby; to :cause the wiperLsha-ft' 111 to bereturned to itsnormal vertical position. .Alsogrupon restoring, the transfer relay Ride completes, at thecontacts 142, .a multiple circuit for energizing Vthe lower winding of theiprex relay R1 611,' this. circuit extending. from ground by way of thecontacts v131 and 142, `the set of switch'springsls182, the contacts 158, 15e and 132arid .the Ylower .'winding ofLRIB toA battery. When .thus energized the 'prex relay Ri te operates onestep vin order to complete, at the contacts 165 thereof, an obvious path, including the grounded control conductor GIDS-of the trunk 155, Vfor shortrcircuitlng the upper winding thereof.

When Vthe'swtching mechanism HS is'released and thewiper shaft 111 is returned'to its Ynormal vertical position, in ',the manner 'previously eX- ,plained the set; of `switch springs S183 is again actuated into engagement and the set `oiswitch springs :Si 82 is: again :actuated into disengagernent. Whenthe set;of;switch springs S182 is `actuated .into disengagement Vthe previously traced .circuit :for energizing 'the lower winding of thepprei-lx relay R16!! and the previously 1nentioned;path forshort-crcuiting theV upper winding of .theipreiix relay R160 are interrupted, vwhereupon an obvious circuit, :including the grounded control conductor Clll'of'the trunk 1&5, is completed Lforsenergizing in series the upperandlower windings .of the prefix relay 4.henthe preX relayRlBfJ is thus energized it takes` .a second Istep oruoperates fully in order to:internupt,at theacontacts 16%,.a further 'common point in the-previously tracedcircuit for energizing the releasemagnetMl'lS and the lower winding thereof. Also, the prex relay Ri interrupts-.atl the contacts' 168, Ia further point. in the previously traced original circuit for cnergin'ng thellower vlwindingthereof and the previously.mentioned path for short-circuiting the upperlwin'ding thereof. "Also, the prefix relay'Riii interrupts, atthe contacts 161, the connection of 'ground-potentialto the switch spring M5 .of 'thesetr-f switch springs S184, and completes,.atthe contacts 162,--a connection between thetest wiper: 1141of the wiper setcarried by the 'wiper-shaft 11 .andthe switch spring 185 of the of `switch springs? S184. `Finally, the prex riiayRlil interrupts, at the contacts 163, the 1.

no allyY completed connection' between the test w' i'iii .and1 the `switchspring 181 of the set of switch springs sltligandrcompletes, at the contacts i E4, `an obvious 'connection between the switch 'springls `oil. the setoffswitch springs S'iiaand the=switch-spring181 of thefset of switch springsSiSli. Accordingly, :at this time, the test wiper liiiis-` connected by way of the contact-S152, the switchsprings185a`rid 18S of the set-ofswitch springs1=S184, the vtest conductor 'C i the contacts 1 [-5, the winding of the switchthrough relay-Rl i0 and the switchsprings [Sii andi of the set of switch springs SISB to the grounded control conductor CIGS of the trunk Yiiijfora purposemore fully explained herein.-

:nerpreviously explained. -At the beginning ci .the .second digitO the transfer relay Rlli reoperates; the hold relay'RI'and the transfer relay RMB being` retained operated during the second digit. Upon operating, thetransfer relay Ri-i completes, at the contacts 141, an alternative circuit for energizing the winding ofV the step relay Rieti, this circuit vextending from ground by way of the contacts 131 and 141, the set of switch springs S180, the contacts 151 and the winding of R150 to battery. When thus'renergized the step relayqR15il reoperates' in order to prepare, at the contacts v1?1, the previously inentionedcircuit for energizing the rotary magnet Mii?, and to complete, at' the ccntacts'152, the previously traced path for short-circuiting the winding Vof the switch-through relay R110. At t .is point, it is again noted thatthe sets*r of switch springs-'S530 and S181 are each actuated into engagement when the :wiper 'shaft 11 1 of the switching mechanism 11@ isdriven one step the vertical direction.

Atthe conclusion of theseconddigit.'0,1the wiper shaft 1 1 1 lof 'the switching; mechanism 119 occupies its tenth Vertical step, `therehy:to1:bring the lower `caro Si@ carriedthereloy` into.` cooperative relationship with respectto'the -rollerf311i carried bythe switch'sipring 135i of the'set of switch springs SISLLinV the'rnannerexplained in conjunctionwith Figs. 3 to`6, inclusive,.:,offthe drawings. Shortly following the conclusion lof the second digit "0' the transfer:relayvRlfrestores,V thereby to complete, at 'the contacts 1112, the previously mentioned circuit" forA energizing the rotary magnetMIl'l, this circuit extending from groundbyfway of the contacts iland' |42, the rotary'rnagnet M111 Iand'thecontacts 151' to battery. When thus venergized vthe 'rotary magnet M211 operates'totdriveV the wiper shaft 111V tive circuit traced hereinafter forenergizing the winding of the step relay R153. Also, the transfer relay Rift@ interrupts, atthe contacts l141, the previously traced original -circuitior lenergizing the winding of the step relayRil, thereby to cause the latter relay to restore. 'Upon're storing, the step relay R150vinterrupts, at fthe contacts E51, the previously traced circuit'forenergizing the rotary magnet M111, thereby Vto cause the latter magnet to restore. Further;I the step relay R55@ interrupts, at'the contactsdg, the previously traced path 'for short-circuiting the winding of the switch-through relayRl 1B. l

At this time, the wiper set carried'by the wiper shaft iii of the switchingmechanism `en gages the' first contact set terminating the trunk Elli in the tenth level intheassociated contact bank and ground potential is connectedby way of the contacts 131, the control conductor Ci S3 of the trunk 195, the switch springs `l89and it@ of the set of switch springs'sl, the winding of the switch-through relay R119, the contacts H5, the test conductor`C125, the switch springs ESS and of the set of switch springs S184 and the contactsv i512 to the test wiper 114 of thewiper set mentioned; rand the idle or busyconditio-n of the trunk 2131 is tested by the selector I.

In the event the trunk 201 is busy at this'time, ground potential appears upon the control Vconductor thereof and is appliedto 'the test wiper ils, thereby to complete an obvious path Vsubf stantially identical to that previously trace'd'for short-circuiting the winding lof the :switchthrough relay Ri 1i) in'order. positively topre'vent operation ofthe latter relay at this time. Also, the last-mentioned application of ground potential toY the test wiper |14 completes a circuit, including the contacts |52, the vswitch springs |85 and |86 of the set of switch springs SI84, the test conductor CI25, the contacts I I5 and |13, the set of switch springs S|80 and the contacts |61, for energizing the winding of the step relay RI50. When the step relay RI 50 is thus energized it operates in order to complete, at the contacts |5I, thefpre'viously traced circuit for energizing the rotary magnet MI11, rwhereupon the latter magnet operates in order to drive the wiper shaft |1| an additional step in the rotary clockwise direction. Furthenthe step relay R|50 completes, at the contacts |52, the previously traced path for short-circuiting the Vwinding of the switchthrough relay R| I in order positively to prevent the latter relay from operating at this time. Also, upon operating, the rotary magnet M|11 interrupts, at the contacts |18, the previously traced circuit, including the test wiper |14, for energizing the winding ofthe step relay RI50, thereby to cause the latter relay! to restore. Upon restoring, ythe'ste'p relay RI50 interrupts, at the contacts II, the previously traced circuit for energizing the rotary magnet M|11 in order to cause the latter magnet to restore. Also, the step relay R|50 interrupts, at the contacts |52, the previously traced path for short-circuiting the windingoi the switch-through relay RIIO. At this time, the wiper set carried by the wiper shaft |1I engages the second contact set in the tenth level in the associated contact bank and the trunk terminated by the last-mentioned wiper set is tested, in the manner explained above. The repeated testing of the various trunks termihated by the contact sets Vin the tenth level in the contact bank |15 proceeds, in the manner explainedA above, until a contact set in the tenth level in the contact bank |15 terminating an idle trunk is tested.

Assuming that the trunk 201 terminated by the seventh Contact set in the tenth level in the contact bank| |15 is the rst idle trunk in the associated group of seven trunks, the wiper shaft |1I'of the switching mechanism |10 is dri-ven in cation of battery potential to the test wiper |14 completes a path, including the contactsy |02, the switch springs |85 and |06 of the set of switch springs S |84, the test conductor CI25, the contacts I|5 and |13, the set of switch springs S|80 and the contacts |61, for short-circuiting the winding of the step relay RI50, thereby positively to rprevent 4further Aoperation thereof and the Vconsequent further operation of the wiper shaft |1I of the switching mechanism |10 in the rotary clockwise direction. Also, the application of 'battery potential to the test wiper |14 completes a circuit, including the contacts |62, lthe switch springs |85 and' |85 of the set of switch springs -S|34, the test conductor CI25, the contacts |I5,

the switch springsA I 00 and |89 of the set of switch springs Siil, the control conductor C|08 of the `trunk |05 and the contacts |3I, for energizing the winding of the switch-through relay RI I0.

When thus energized the switch-through relay RI I0 operates to interrupt, at the contacts I| 5, the previously traced path for short-circuiting the winding of the step relay RI50, and to complete, at the contacts IIB, `a path, including the contacts itl, the test conductor CI25, the switch springs and |85 of the set of switch springs SIM and the contacts |62, for applying direct ground potential to the test wiper |14. The application of direct ground potential to the test wiper |14 causes operation of the connector 232 terminating the trunk 201, the trunk 201 being terminated by the seized seventh contact set in the tenth level in the contact bank |15 of the switching mechanism |10, as previously explained. More particularly, the connector 232 operates in order to return ground potential over the control conductor of the trunk 201 and consequently over the test wiper |14. When ground potential is thus returned over the test wiper |14 a holding circuit is completed for energizing in series the winding of the switch-through relay R|I0 and the winding of the step relay RI50, this circuit extending from 'the grounded test wiper |14 by way of the contacts |02, the switch springs and |86 of the set of switch springs SIM, the test conductor CI25, the contacts IIB, the control conductor CI08 of the trunk |05, the switch springs |89 and |90 of the set of switch springs SISB, the winding of RIID, the contacts |13, the set of switch springs SI80, the contacts |51 and the winding of R|50 to battery. When this series holding circuit is completed the switch-through relay RI I0 is retained in its operated position; however, the step relay R|50 does not operate 'due to the high series resistance ofthe winding of the switch-through relay RI I0.

Also, upon operating, the switch-through relay R|I0 interrupts, at the contacts I|1, the previously traced circuit for energizing the winding 0f the hold relay RI30, thereby to cause the latter relay to restore shortly thereafter, the hold relay R|30 being of the slow-to-release type, as previously noted. Upon restoring, the hold relay RISO interrupts, at the contacts |3I, the previously traced path for applying ground potential in the selector |00 to the control conductor CI08 of the trunk |05. However, at this time, ground potential is applied to the control conductor CI08 of the trunk |05 by watr of the previously traced circuit, including the test wiper |14, from the connector 232. Hence, the selector |00 and the line switch |02 are retained in their operated positions and the marking of the subscriber line IOI as busy to the connectors having access thereto is retained. Further, the switch-through relay RIIO interrupts, at the contacts I I and I3, the previously traced loop circuit extending between the calling subscriber substation 'II and the line relay RI20 in the selector |00, thereby to deenergize the upper and lower windings of the line relay R|20 in order to cause the latter relay to restore. Finally, the switch-through relay RII 0 completes, at the contacts ||2 and H4, a loop circuit extending between the calling subscriber substation T| and the connector 232. This loop circuit extends from the line conductor C|06 of the trunk |05 by way of the contacts ||2 and the line wiper |12 to one of the line conductors of the trunk 201, and from the line conductor C |01 ofthe trunk |05 by way of the contacts I|4 and the line wiper |13 to the other line conductor of the trunk 201; the line conductors CIGS and C|01 of the trunk |05 being battery potentials in the. connector F232.

vswitchh-oolr. 'Gn the .other `the calledsubscriber` substation :T2 is idlefiat this timer the connector f'l operates `in `order ila-3 115,010

. connectedtogether'- at the calling-:subscriber substation .TI bywaylof the zline switch I02aan'd of the trunk 2U? being` connecteur toJgrOund-and Atthis time, the connectorSZ is in readinessto receive the last two digitsXX.

The subscriberatthe calling subscriber substation TI then '..proceeds to :dial .thelasttwo digits which digitslaref transmitte'dioverlthe .previously .traced loo-p circuit to f the connector 232 in .order tocause the last-mentionedponnector to operatein'awell-known'lmannerto vseize the subscriber 'line 1230: extending Ytofithe called subscribersubstationTL The subsequent operation o the connector "2 321depends uponthe .idle or busy-condition-of the called fsubsciiber substation T2, in Vaccordance"vi/*ith.conventional practice. In theevent the called subscriber substation T2 is busy at this time, "the/connectory232 operates in order to .cause busy tone four- .rent-to be returned over the trunk 261, the

selector.- Iil, .the trunk N5, "theriline .switch l'fZ and the subscriber'line -illl to -.the"ca'lling subscriber substation TI; whereupon thei subscriber at theV calling subscriber .substation TI 'releases the connection by` replacing the "receiver1 'of the telephone instrument thereatupon its 'associated handgin the :event to cause ringing currenttobe .projectedfover the Subscriber line 230, andtofcauseringeback tone cur-rent to bel returned over the tru'nkg,

iheeselector itil, the trunk vI)5,.the linefswitch y |02 and the subscriber'li-ne 'MI 'to the-:calling subscriberfsubstation TI. Inlthis fevent, after the-subscriber atthe'called subscriber substation T2 answers'the call by-removing the rre- .ceiver 'ofthe telephone instrument thereat from its :associated 'switohhook, vthe connector `232 .operates in order to complete f`an Yobviousfcon- .nection between the-` calling subscriber ;substa tion Yl'l -andthe. calledA 'subscriber 'substation TF2,

this connection including the subscriber li-ne' WI,

the line switch It?, they trunk l d5; the. selector lili), the trunk Bill, the connector 232 fand-the subscriber. line 23u. Also, itV isA noted' that-when the connector 232 operates toseize thesubscriber line-23l3 extending torthe called subscriber w substation ground'potential isappliedtothe control conductor thereof.Y thereby to'rnark' the subscriber line '-Siras :busy to the *other 'ccnnecto-rs having access thereto.

The release of thisV established-connection is g primarily under the controlzoff the. subscriber-at the calling-subscriber substation TI Aand -s-.ei-fective whenV the-subscriberat thecalling.- subscriber substation 'TI replaces the'receiver Aof-the-telephone instrument the-reat .upon its .fassociated switchhook in order to interrupt the-previously traced loop circuit extending between'the calling subscriber substation TI and thefconn'ectorl232. When the loop circuit mentioned isthus interrupted the connector 232sis`released inord'erfto g:

interrupt the application orground potential rto the control conductor of the trunk 2l!V extending thereto. When ground potential-is thus removed from the control conductorof the trunk-2li1 and consequently from the test wiper H4 and vthe control conductor CIGS o'the trunk |05,` the line switch H32 is released, whereuponl the subscriber line IiV extending to the calling subscriber substation TI is markedf as idletorthe': connectors having access thereto. Further,- when :fground potential is removed fromlthe control conductor 1C m8 of :the trunk IU 5 the' previously traced holding `circuit forr energizing' in seriesthezwinding vof 'the iswitchzthrough relay'` RI I0 and the' winding of the step relayaRISt is interrupted;A thereby to Lcausethe switchthrough relay R! I0 to restore. :Upon restoring,' the switch-through relay RI Il) completes, at theicontacts I I'I, an obvious circuit, :including the contacts |22 and |34, andthe setof -switch springsSIBLior energizing'the release .s'magnetMI'I When the release magnetlMI'I-S fisthusenergize'd it operates to release the Switch- `ing: mechanism |10, whereby the vvipershaft` I'II :isreturned first to its normal rotary position and fthen to 'its normal vertical position. Whenfithe tswitching mechanism I'I is thus releasedfeach of -thelsets of switch springs SIB() and SIBI isactu- 'atedzinto disengagement, the previously .traced ,circuit 'for energizing the release-magnet M'IIl ibeinglinterrupted when the rset of switch springs `'TSISI is actuated into disengagement. Finally, it isl'notedl that when lground :potential is removed from the control conductor() Hi8 of: the trunk IDS the previously traced holding circuit for energizingin. series the upper and lower windings of the :prefix relay Riti! is interrupted, thereby to cause ther latter relay to restore. fAt this time, the selectorI i!!! is completely/released.

fFurther, itis noted that when the connector 232 is released the subscriber line' 230 is marked das idle L to the i other connectors having access f thereto; assuming that the subscriber at the called subscriber substationlTZ has'replaced the receiver -ofthetelephone instrument there'at upon its asso'ciated switchhook atthis time. Accordingly', at this'ltime, the established connection between the "calling subscriber substation JT! :and the called :subscriberzsubstation F2-is completely released .rand'the apparatus previously employed therein is :available for further. use.

nthe foregoingexplanation oi` the mode of roperattioniof the selector.' Illl incident to the vex- .tensionrofgarcall from the :calling subscriber lsublstationfl to the called subscriber substation'TZ, Tit Waszassurned' that there was an idlev trunk in .the'group YoiisevenA terminated `by the first seven 1contactisets in the'tenth levelzin the contact bank iIIS of Ythe s'witching'mechanism I'I and extending to: the variousrconnectors, `including the conhector-232; hovveven'it 'may'occur'` that there is .no idle trunk 'inthe group-intentioned incident' to roperationiof the selector" Il in'response .to the fseconddigit'f'aftertheprex digit 2 has been dialed,in themannerexplained above. In this -event,after the'selector It@ respondsto the secfondsdigit 0, Yin the manner explained above, oper- .ationthereof is initiated Pto 'test 'the various trunksirin the 'group mentioned in thezgmanner previously explained However, in this tevent, thereis no idle trunk inthe igroupmentioned; accordingly, the wiper shaft I'Il is driven step by step inthe rotaryclockwisedirection past the seventh 'step-and intothe eighth step thereof .array` --ronrits normal rotary :positi on.

fAt'this point,v it isfnoted that'the lower cam Sill-carried by the wiper-4 shaftv Il Stand positioned .adjacent the roller'f's-i'd isso adjusted that 'when the `Wipershaft il! isdriven'eight steps in the rotaryclockwise' direction' the-second cam surface i3 I 810i'. the vlowcr carrrBl-Sl operates the roller 3 I 3 carried Yby the switchspring' IG, whereupon the switch springs 35.v andl .of .the set of :switch springs-Site are: actuatedinto disengagement and theeswit'chv springs `Iiiii and AIM'. of` the setfof ment. Hence, at this time, the testv conductor 'CI 25 is disconnected from the test wiper |14 and is connected to the set of switch springs SI 9|; whereupon direct ground potential is applied by way of the switch springs Il and |93 of the set of switch springs Sidl, the contacts |64, and the switch springs I 31 and |86 of the set of switch springs SIB4 to the test conductor CI25. Accordingly, it will be understood that, when the Wiper set carried by the wiper shaft I1I is rotated to engage the eighth contact set in the tenth level in the contact bank |15, the set of switch springs Si 84 is actuated, whereby there is no testing of the last three trunks in the group, including the trunks 2538 and 2&9, terminated by the last three contact sets in the tenth level in the contact bank and extending to the manual operator position (l. Hence, at this time, the step relay RIS!) and the rotary magnet MI11 interact, in the manner previously explained, whereby the wiper shaft I1I of the switching mechanism |10 is automatically driven step by step eleven steps away from its normal rotary position.

When the wiper shaft I'II of the switching mechanism |10 is driven eleven steps away from its normal rotary position the cam surface 3I9 provided on the bracket :iii-3 engages the roller 3M carried by the switch spring |85, thereby to eiTect operation of the sets of switch springs -SI88, SIQI and SI94, in the manner explained in conjunction with Figs. 3 to 6, inclusive, of the drawings. More particularly, the switch springs |89 and |99 of the set of switch springs S|88 are actuated into disengagement, thereby to interrupt a point in the connection between the control conductor C |68 of the trunk |05 and the winding of the switch-through relay RI I0. This arrangement positively prevents operation of the switch-through relay RI IlI when the switch springs |92 and |93 of the set of switch springs SISI are actuated into disengagement. Also, the switch springs |92 and |93 of the set of switch springs SISI are actuated into disengagement, thereby to interrupt the previously traced circuit for energizing the winding of the step relay Rlll in order to cause the latter relay to restore, thereby to prevent further operation of the rotary magnet MHT. Also, the switch springs |96 and I 91 of the set of switch springs SI94 are actuated into disengagement, and the switch springs |95 and ISS of the set of switch springs SISII are actuated into engagement; whereupon an obvious alternative loop circuit, including the busy tone conductor CI03, is completed between the calling subscriber substation Tl and the line relay RIZi! in the selector IM). When this alternative loop circuit is completed, busy tone current is returned from the selector |00 over the trunk |05, the line switch |02 and the subscriber line IDI to the calling subscriber substation TI, thereby to indicate to the subscriber at the calling subscriber substation TI that the desired connection may not be had immediately due to the all-busy condition of the trunks in the desired group appearing before the selector Iili, as explained above. The subscriber at the calling subscriber substation Ti then proceeds to release the selector Iii@ and the line switch |82 by replacing the receiver cf the telephone instrument at the calling subscriber substation TI upon its associated switchhook, in the manner previously explained.

In view of the foregoing explanation of the mode of operation of the selector H30 to extend a call from the calling subscriber substation TI to the called subscriber substation T2.

it will be ate and drive the wiper shaft understood that a call may be extended from any calling subscriber substation to any called subscriber substation, in a substantially identical manner, by the selector I 30 and an idle connector in the appropriate group in response to the preiix digit 2 and the digits YXX, wherein the digit Y represents the ten groups of connectors and the digits XX represent the vertical and rotary positions of the called subscriber line before the various connectors in the desired group. In this connection, it is pointed out that, in the event the directory number of the called subscriber substation comprises the digits 21XX, the operation of the selector I6 is substantially identical to that explained above, except that the upper cam SIB carried by the wiper shaft III is utilized to operate the set of switch springs SIM in this case. Also, in this case, the upper cam BIB is adjusted with respect to the wiper shaft I1| so that the roller 3I4 carried by the switch spring I 86 is actuated thereby when the wiper shaft I'II is moved six steps in the rotary clockwise direction away from its normal rotary position after it has been previously moved one step in the vertical direction away from its normal vertical position. This arrangement positively insures that the trunks in the group, including the trunks 2IS and ZIB, terminated by the last five contact sets in the first level in the contact bank |15 of the switching mechanism |10 and extending to the group of special service selectors, are not tested by the selector Idil, in the example mentioned.

Considering now the extension of a call from a subscriber substation, such, for example, as the subscriber substation TI, to the manual operator position 0, the call is rst initiated at the calling subscriber substation TI, in the manner previously explained. Again assuming that the line switch |02 individually connected to the subscriber line IIlI extending to the calling subscriber substation TI is operated to seize the trunk m5 extending to the selector it, the previously traced loop circuit extending between the calling subscriber substation TI and the line relay RI 20 in the selector IDI! is again completed.

The subscriber at the calling subscriber substation TI then proceeds to dial the single digit 0, thereby to cause the line relay RIE@ in the selector I to follow the impulses of the digit mentioned. At this time, both the hold relay RISIJ and the transfer relay RME! occupy their operated positions and the vertical magnet MHS is energized and deenergized ten times, in the manner previously explained; whereupon the wiper-'shaft |1I is driven ten steps in the vertical direction away from its normal vertical position. At the conclusion of the digit 0, the step relay Rl occupies its operated position, thereby to retain prepared, at the contacts I5I, the previously traced circuit for energizing the rotary magnet MITI, and to retainvcompleted, at the contacts |52, 4the previously traced path for shortcircuiting the winding of the switch-through relay RI I0. Also, at this time, each of the sets of switch springs SISiI and SEBI is actuated into engagement.

Shortly following the conclusion of the digit 0 the transfer relay RI/J restores, this relay being of the slow-to-release type, as previously noted. Upon restoring, the transfer relay Ril cempletes, at the contacts M2, the previously traced circuit for energizing the rotary magnet MI11, thereby to cause the rotary magnet Mi 'I1 to oper- I1I one step in the rotary clockwise direction away from its normal rotary position. Also, the transfer relay R140 interrupts, at the contacts lili, the previously traced circuit for energizing the winding of the step relay R158, thereby to cause the latter relay to restore. Upon restoring, the step relay R159 interrupts, at the contacts 151, the previously traced circuit for energizing the rotary magnet M177, thereby to cause the rotary magnet Mll'i to restore. Upon restoring, the rotary magnet Mil? completes a direct ground circuit for energizing the winding of the step relay R150, this circuit extending from ground by way oi the contacts Kil, the switch springs 1&5 and 1.86 of the set of switch springs Si, the test conductor C125, the contacts H5 and llt, the sets of switch springs 518i! and S183 and the winding of R15ii to battery. When thus energized the step relay R156 reoperates. In the present example, the step relay R158 and the rotary magnet M117 interact in the manner explained above, thereby to cause the wiper shaft |71 to be driven automatically step by step in the rotary clockwise direction eight steps away from its normal rotary position. lt is again noted that, when the wiper shaft ll of the switching mechanism Iil is driven eight steps in the rotary clockwise direction away from its normal rotary position, the lower cam Lil carried by the wiper shait 111 operates the roller 3i@ carried by the switch spring 13S; whereupon'the switch springs 185 and 18S of the set of switch springs Sii are actuated into disengagement and the switch springs 13S and 18l of the set of switch springs SiSd are actuated into engagement. Also, at this time, the wiper set carried by the wiper shaft Vil engages the eighth contact set in the tenth level in the associated contact bank H5 terminating the trunk 2055 extending to the manual operator position El. connected by way of the contacts H53, the switch springs ii and 18E of the set of switch springs S1811, the test conductor Ci and the contacts H5 to the winding of the switch-through relay Rilii. Accordingly, the idle or busy condition of the trunk 238 extending to the manual operator position ii is tested, in the manner previously explained.

In view ci the foregoing explanation of the mode of operation of the selector ll in response to the single digit O, it will be understood that the wiper set carried by the wiper shaft 111 of the switching mechanism Vit is automatically driven in the rotary clockwise direction over the rst seven Contact sets in the tenth level in the associated contact bank V15 without testing the trunks terminated by the Contact sets mentioned; and that the trunks terminated by the last three contact sets in the tenth level in the associated contact bank V15 are then progressively tested, in the manner previously explained.

This arrangement positively insures that theV selector l will not respond to the digit 0 and select an idle trunk in the group, including the trunks 2M and Eil?, extending to the various connectors in the tenth group.

As previously explained, when the wiper set carried by the wiper shaft 1li of the switching mechanism l engages the eighth contact set in the tenth level in the associated contact bank 115 the trunk extending to the manual operator position ii is tested by the selector i533; and further operation of the switching mechanism H3 is eected only in the event the trunk 2438 is tested as busy, in the manner previously ex- At this time, the test wiper lili is f plained. Assuming that the trunk 200 terminated by the tenthv contact set in the tenth level in the contact bank 115 is the rst idle trunk in the group of three extending to the manual operator position U, further operation of the switching mechanism lli) is eiected in order to cause the wiper shaft 1'11 tov be driven ten steps in the rotary clockwise direction away from its' normal rotary position. Attn-is time, the wiper set carried by the wiper. shaft 1'11y engages the tenth contact set in the tenth level in. the associated contact bank H5 terminating the idle trunk 20d, thereby to cause the selector li to switch through, in the manner previously explained. At this time, the call is'ext'ended from the calling subscriber substation TI to the manual operator position i) by way of the subscriber line lill, the line switch lEiZ, the trunk |65, the selector lili! and the trunk lil. At this point, it is noted that the trunk circuit associated with the trunk 2&0 operates when the last-mentioned trunk is seized by the selector lili) in order to cause ground potential to be returned over the control conductor thereof to the testk wiper IN. This application of ground potential to the test wiper V14 retains the selector l-' and the line switch H32 in their operated positions and retains the subscriber Yline di marked as busy to the connectors having access thereto, in the manner previously explained; Further, when the trunk 'Edil is thus seized by the selector llllll a signal at the manual operator position il' is operated in order to indicate to the operaterI thereat that this trunkhas vbeen seized. The operator at the manual operator position 0- then answers the call', thereby to complete the previously traced established 4connection. The release of this established connection between the calling subscriber substation-T1 and the manual operator position d is primarily under the control of the subscriber at the calling subscriber substation` TI and is effected, in the manner previously explained', when the subscriber at the calling subscriber substation TI replaces the receiver ofthe telephone instrument thereat upon its associated switchhook.

In the foregoing explanation of Ithe mode of operation of the selector liY incident to the extension of a call from the calling subscriber substation TI to the called manual operator position il, it was assumed that there was an idle trunk'in the group of three terminated by the lastY threeried bythe switch spring F86' in order to actuate the sets of switch springsV S138, Siti and S194, inthe manner previously' explained; When the set of switch springs S-id is thus actuated, busy tone current is returned over thev loopcircuit extending betweenl the calling subscriber substation T1' and the line relay R120 in tl`1e-sel'ectorV 1601, in-

the manner previously noted; whereupon the subscriber at theA calling subscriber ysubstation TI' effects the release of the line switch 102 and the selector 10U by replacing the receiver of the telephone-instrumentthereat upon its associated switch'hook, in the` manner previously explained.

Considering no'w'the extension of a call from a subscriber substation, such, for example, as theV subscriber substation TI, to the toll operatorposition I l0, the call is rst initiated at the calling subscriber substation TI, in the manner previously explained. Again assuming that the line switch" |02 individually connected to the subscriber line IOI extending to the calling subscriber substation VTI is operated to seize the trunk |05 extending to the selector |00, the previously traced loop circuit extending between the calling subscriber substation TI and the line relay RI 20 in the selector |00 is again completed.

.The subscriber at the calling subscriber substation TI then proceeds to dial the digits 110, thereby to cause the line relay RI20 in the selector to follow the first digit 1. At this time, both the hold relay R|30 and the transfer relay R|40 occupy their operated positions and the vertical magnet MI16 is energized and deenergized once, in the manner previously explained; whereupon the wiper shaft I1I is driven one step in the vertical direction away from its normal vertical position. At the conclusion of the iirst digit 1, the step relay RI50 occupies its operated position, thereby to retain prepared, at the contacts I5I, the previously traced circuit for energizing the rotary magnet MI11, and to retain completed, at the contacts |52, the previously traced path for short-circuiting the winding of the switch-through relayv RIIII. Also, at this time, each of the sets of switch springs SI80 and S I 8| is actuated into engagement.

lShortly following the conclusion of the nrst digit 1, the transfer relay R|40 restores, this relay being of the sloW-to-release type, as previously noted. Upon restoring, the transfer relay R|40 completes, at the contacts |42, the previously traced circuit, for energizing the rotary magnet MITI, thereby to cause the rotary magnet M|11 to operate and drive the wiper shaft |1| one step in the rotary clockwise direction away from its normal rotary position. A1so, the transfer relay RI40 interrupts, at the contacts I4I, the previously traced circuit for energizing the winding of the step relay R150, thereby to cause the latter relay to restore.V Upon restoring, the step relay R|50 interrupts, at the contacts |5I, the previously traced circuit forenergizing the rotary magnet MI11, thereby to cause the rotary magnet MI11 to restore. Upon restoring, the rotary magnet M|11 completes a direct ground circuit for energizing the winding of the step relay RI50, this circuit extending from ground by way of the contacts IBI, the switch springs |85 and |85 of the set of switch springs SI84, the test conductor CI25, the contacts |I5 and |18, the sets of switch springs S|80 and SI83 and the winding of R|50 to battery. When thus energized the step relay R|50 reoperates. In the present example, the step relay R|50 and the rotary magnet M|11 interactin the manner explained above, thereby to cause the wiper shaft I1I to be driven automatically step by step in the rotary clockwise direction six steps away from its normal rotary position. It is again noted that, when the wiper shaft |1| of 'the switching mechanism is driven six steps in in the rotary clockwise direction away from its normal rotary position, the upper cam 3I0 carried by the wiper shaft |1I operates the roller` 3I4 carried by the switch spring |86, whereupon the switch springs |85 andA |86 of the set of switch springs S|84 are actuated into disengagement and the switch springs |86 and |81 ofthe set of switch springs SI84 are-actuated into en- 75 gagement. Also, at this time, the wiper set carried by the wiper shaft I1I engages the sixth contact set in the first level in the associated contact bank |15 terminating the trunk 2IS extending to the special service selector 233. At this time, the test wiper |14 is connected by way of the contacts |53, the switch springs |81 and |88 of the set of switch springs SIM, the test conductor CI25 and the contacts I I5 to the winding of the switch-through relay RI I0. Accordingly, the idle or busy condition of the trunk 2 I6 extending to the special service selector 233 is tested, in the manner previously explained.

In view of the foregoing explanation of the mode of operation of the selector |00 in response to the iirst digit 1, it will be understood that the wiper set carried by the wiper shaft |1| of the switching mechanism |10V is automatically driven in the rotary clockwise direction over the iirst ve contact sets in the iirst level in the associated contact bank |15 without testing the trunks terminated by the contact sets mentioned; and that the trunks terminated by the last five contact sets in the iirst level in the associated contact bank |15 are then progressively tested, in the manner previously explained. rlhis arrangement positively insures that the selector |00 will not respond to the first digit l and select an idle trunk in the group, including the trunks 2|I and 2|5, extending to the various connectors in the first group.

As previously explained, when the wiper set carried by the wiper shaft I1I of the switching mechanism |10 engages the sixth Contact set in the rst level in the associated contact bank |15, the trunk 216 extending to the special service selector 233 is tested by the selector |00; and further operation of the switching mechanism |10 is effected only in the event the trunk 2|6 is tested as busy, in the manner previously explained. Assuming that the trunk 2|6 terminated by the sixth contact set in the iirst level in the contact bank |15 is the rst idle trunk in the group of five extending to the special service selector 233, etc., no further operationl of the switching mechanism |10 is effected. At this time, the call is extended from the calling subscriber substation TI to the special service selector 233 by Way of the subscriber line IUI', the line switch |02, the trunk |05, the selector |00 and the trunk 2 I0. At this point, it is noted that the trunk circuit associated with the trunk 2I6 operates when the last-mentioned trunk is seized by the selector |00 in order to cause ground potential to be returned over the control conductor thereof to the test wiper |14. This application of ground potential to the test Wiper |14 retains the selector |00 and the line switch |02 in their operated positions and retains the subscriber line |0| marked as busy to the connectors having access thereto, in the manner previously explained. Further, when the trunk 2|6 is thus seized by the selector |00 the special service selector 233 is rendered responsive to the second digit 1.

The special service selector 233 then responds to the second digit 1 Vand drops black in a wellknown manner; at which time it is rendered resporisive to the third digit 0. Finally, the special service selector 233 responds to the third digit 0 in order to hunt for an idle trunk in the group extending to the toll operator position IIB. The subsequent operation of the special service selector 233 depends upon the idle or busy condition of the trunks in the group extending to the toll operator position HS, in a well-known manner. Assuming that the trunk 234 in the group mentioned is the iirst idle trunk, the special service selector 233 operates to seize the trunk 23d, whereupon a signal is transmitted thereover to the toll operator position lib in order to indicate to the operator thereat that this trunk has been seized. The operator at the toll operator position HS then answers the call, thereby to complete the previously traced established connection. The release of this established connection between the calling subscriber substation Tl and the toll operator position Htl is primarily under the control of the subscriber at the calling subscriber substation Tl and is eiected, in the manner previously explained, when the subscriber at the calling subscriber substation 'Il replaces the receiver of the telephone instrument thereat upon its associated switchhook.

In view of the foregoing explanation of the mode of operation of the selector lim and the special service selector 233 to extend a call from the calling subscriber substation Ti to the toll operator position il@ in response to the digits 110, it will be understood that this apparatus is operative, in a simiiar manner, in response to the digits 112 and 113, respectively, to extend a call from the calling subscriber substation TI to the miscellaneous operator position H2 and the information operator position H3.

In the foregoing explanation of the mode of operation or the selector iii incident to the eX- tension of a call from the calling subscriber substation 'Il to the called toll operator position l it was assumed that there was an idle trunk in the group of ve terminated by the last ve contact sets in the rst level in the Contact bank I'i of the switching mechanism l and extending to the special service selectors 233, etc.; however, it may occur that there is no idle trunk in the group mentioned incident to operation of the selector im in response to the first digit l. in this event, the wiper shaft I'H of the switching mechanism Vid is driven eleven steps in the rotary clockwise direction, whereupon the bracket 3&3 carried thereby operates the roller 3l@ carried by the switch spring 185 in order to actuate the sets of switch springs Sl88, SISI and Sled, in the manner previously explained. When the set of switch springs S194 is thus actuated, busy tone current is returned over the loop circuit extending between the calling subscriber substation T! and the line relay RIZil in the selector l G, in the manner previously noted; whereupon the subscriber at the calling subscriber substation Ti effects the release of the line switch m2 and the selector |60 by replacing the receiver of the telephone instrument thereat upon its associated switchhock, in the manner previously explained.

While there has been described what is at present considered to be the preferred embodiment of the invention, it will be understood that various modifications may be made therein and it is intended to cover in the appended claims all such modications as fall within thel true spirit and scope of the invention,

What is claimed is:

l. In a signaling system, an automatic switch comprising a wiper set including two line wipers and a single test wiper, a terminal bank cornprising terminal sets arranged in levels accessible to said wiper set, two groups of trunks terminated by the terminal sets in a given level of said bank, each of said trunks including two line conductors and a single test conductor, mechanism selectively operable to determine either one of said groups of trunks in said givenlevel, means for initiating movement of said wiperrset over the terminal sets in said given level, means governed by said mechanism for testing over said test wiper the test conductors of the trunks in the previously determined one of said groups, and means governed by said last-mentioned means for arresting movement of said wiper set, whereby said wiper set is controlled to select an idle trunk in said previously determined one of said groups.

2. In a signaling system, a line, an automatic switch associated with said line and comprising a wiper set including two line wipers and a single test wiper, a terminal bank comprising terminal sets arranged in levels accessible to said wiper set, two groups of trunks terminated by the terminal sets in a given level of said bank, each of said trunks including two line conductors and a single test conductor, mechanism operable to determine either one of said groups of trunks in said given level, means controllable over said line for selectively operating said mechanism, additional means controllable over said line for initiating movement of said wiperset over the terminal sets in said given level, means governed by said mechanism for testing over said test wiper the test conductors of the trunks in the previously determined one of said groups, and means governed by said last-mentioned means for arresting movement of said wiper set, whereby said wiper set is controlled to select an idle trunk in said previously determined one of said groups.

3. In a telephone system, a telephone station, a line extending to said station, an automatic switch comprising a wiper set including two line wipers and a single test wiper, means responsive to initiation of a call at said station for connecting said line to said switch, a terminal bank comprising terminal sets arranged in levels accessible to said wiper set, two groups of trunks terminated by the terminal sets in a given level of said bank, each of said trunks including two line conductors and a single test conductor, mechanism operable to determine either one of said groups of trunks in said given level, means controllable from said station over said line for selectively operating said mechanism, additional means controllable from said station over said line for initiating movement of said wiper set over the terminal sets in said given level, means governed by said mechanism for testing over said test wiper the test conductors of the trunks in the previously determined one of said groups, means governed by said last-mentioned means for arresting movement of said wiper set, whereby said wiper set is controlled to select an idle trunk in said previously determined one or" said groups, and means responsive to the selection by said wiper set or" said last-mentioned trunk for connecting said line to said wiper set.

4. In a signaling system, an automatic switch including a wiper, first and second groups of terminals accessible to said wiper, mechanism operable between two positions respectively corresponding to said first and second groups ofv to determine a corresponding one of said groups.

of terminals, a tester, means governed when said mechanism occupies a prepared one of its positions for rendering effective said tester, means for initiating movement of said wiper successively to engage the terminals in said rst and second groups, means responsive to movement of said wiper over the terminals in said rst group and into engagement with the rst terminal in said second group for operating said mechanism from one of its positions to the other, whereby said mechanism is operated from a prepared position to an unprepared position or from an unprepared position to a prepared position, said tester being operative when it is rendered eiective to test each terminal engaged by said wiper, and means controlled by said tester in response to the testing as idle of a terminal engaged by said wiper for arresting movement of said wiper, whereby said wiper is controlled to select an idle terminal in the previously determined one of said groups.

5. In a signaling system, an automatic switch including a Wiper, first and second groups of terminals accessible to said wiper, a test conductor,

- mechanism operable between two positions respectively corresponding to said first and second groups of terminals, means for selectively preparing either one of the positions of said mechanism, thereby to determine a corresponding one of said groups of terminals, means controlled when said mechanism occupies a prepared one of its positions for connectingsaid test conductor to said wiper, means for initiating movement of said wiper successively to engage the terminals in said iirst and second groups, means responsive to movement of said wiper over the terminals in said first group and into engagement with the rst terminal in said second group for operating said mechanism from one of its positions to the other, whereby said mechanism is operated from a prepared position to an unprepared position or from an unprepared position to a prepared position, and means controlled when said test conductor is connected to said wiper and in response to the engagement by said wiper of an idle terminal for arresting movement of said wiper, whereby said wiper is controlled to select an idle terminal in the previously determined one of said groups.

6. In a signaling system, an automatic switch including a wiper, first and second groups of terminals accessible to said wiper, a test conductor, mechanism operable between two positions respectively corresponding to said rst and second groups of terminals, means for selectively preparing either one of the positions of said mechanism, thereby to determine a corresponding one of said groups of terminals, means controlled when said mechanism occupies a prepared one of its positions for connecting said test conductor to said wiper, means for initiating movement oi said wiper successively to engage the terminals in said rst and second groups, means responsive to movement of said wiper over the terminals in said rst group and into engagement with the rst terminal in said second group for operating said mechanism from one of its positions to the other, whereby said mechanism is operated from a prepared position to an unprepared position or from an unprepared position to a prepared position, means controlled when said test conductor is connected to said wiper and in response to the engagement by said wiper of an idle terminal for arresting movement of said wiper, whereby s-aid wiper is controlled to select an idle terminal in the previously determined one of said groups, and additional means responsive to movement of said wiper over the last terminal in said second group for arresting movement of said wiper.

7. In a signaling system, an automatic switch including a wiper, rst and second groups of terminals accessible to said Wiper, a test conductor, mechanism operable between Atwo positions lrespectively corresponding to said first and second groups of terminals, means for selectively preparing either one of the positions of said mechanism, thereby to determine a corresponding one of said groups of terminals, means controlled when said mechanism occupies other than a prepared one of its positions for impressing a guard potential upon said test conductor, means for initiating movement of said wiper successively to engage the terminals in said first and second groups, means responsiveto movement of said wiper over the terminals in said first group and into engagement with the first terminal in said second group for operating Said mechanism from one of its positions to the other, whereby said mechanism is operated from a prepared position to an unprepared position or from an unprepared position to a prepared position, and means conincluding a wiper, rst and second groups of terminals accessible to said wiper, a test conductor, mechanism operable between two positions respectively corresponding to Said first and second groups of terminals, means for selectively preparing either one of the positions of said mechanism, thereby to determine a corresponding one of said groups of terminals, means controlled when said mechanism occupies a prepared one of its positions for connecting said test conductor to said wiper and controlled when said mechanism occupies other than its prepared positions for impressing a guard potential upon said test conductor, means for initiating movement of said wiper successively to engage the terminals in said first and second groups, means responsive to movement of said wiper over the terminals in said first group and into engagement with the rst terminal in said second group for operating said mechanism from one of its positions to the other, whereby said mechanism is operated from a prepared position to an unprepared position or from an unprepared position to a prepared position, additional means controlled when said test conductor is connected to said wiper and said wiper engages a busy terminal for impressing said guard potential upon said test conductor, and means responsive to the absence of said guard potential upon said test conductor for arresting movement of said wiper, whereby said Wiper is controlled to select an idle terminal in the previously determined one of said groups.

9. In a signaling system, a trunk, an automatic switch associated with said trunk and including a wiper, first and second groups of terminals accessible to said wiper, a test conductor, mechanism operable between two posi-tions respectively corresponding to said first and second groups of terminals, means controllable over said trunk for selectively preparing either one of the positions of said mechanism, thereby to determine a corresponding one of said groups of terminals, means controlled when said mechanism occupies a prepared one of its positions for connecting said test conductor to said Wiper, additional means controllable over said trunk for initiating movement of said Wiper successively to engage the terminals in said rst and second groups, means responsive to movement of said wiper over the terminals in said first group and into engagement With the first terminal in said second group for operating said mechanism from one of its positions to the other, whereby said mechanism is operated from a prepared position to an unprepared position or from an unprepared position to a prepared position, and means oontrolled when said test conductor is connected to said Wiper and in response to the engagement by said wiper of an idle terminal for arresting movement of said Wiper, whereby said wiper is controlled to select an idle terminal in the previously determined one of said groups.

10. In a signaling system, a trunk, an automatic switch associated with said trunk and including a wiper, first and second groups of terminals accessible to said Wiper, a test conductor, mechanism operable between two positions respectively corresponding to said Iirst and second groups of terminals, means controllable over said trunk for selectively preparing either one of the positions of said mechanism, thereby to determine a corresponding one of said groups of terminals, means controlled when said mechanism occupies a prepared one of its positions for connecting Said test conductor to said wiper, addi- Y tional means controllable over said trunk for initiating movement of said wiper successively to engage the terminals in said first and second groups, means responsive to movement of said wiper over the terminals in said iirst group and into engagement with the iirst terminal in said second group for operating said mechanism from oneof its positions to the other, whereby said mechanism is operated from a prepared position to an unprepared position or from an unprepared position to a prepared position, means controlled when said test conductor is connected to said wiper and in response to .the engagement by said wiper oi an idle terminal for arresting movement of said wiper, whereby said Wiper is controlled to select an idle terminal in the previously determined one of said groups, and additional means responsive to movement of said Wiper over thelast terminal in said second group for arresting movement of said Wiper and for impressing a busy signal upon said trunk.

ll. In a signaling system, an automatic switch of the primary-secondary motion type including a wiper set having access to an associated terminal bank arranged in levels, rst and second groups oi trunks terminated in a given level of said bank, mechanism operable between two positions respectively corresponding to said first and second groups of trunks, means for selectively preparing either one of the positions of said mechanism, thereby t-o determine a corresponding one of said groups of trunks, means for imparting primary movement to said wiper set to said given level, means for initiating secondary movement of said Wiper set in said given level successively to engage the trunks in said rst and second groups, means responsive to secondary movement of said wiper set in said given level over said first group oi" trunks and into engagewith the first trunk in said second group oi trunks for operating said mechanism from one of its positions to the other, whereby said mechanism is operated from a prepared position to an unprepared position or from an unprepared position to a prepared position, and means controlled when said mechanism occupies its prepared position and in response to the engagement by said wiper set of an idletrunk for arresting secondary movement of said Wiper set, whereby said Wiper set is controlled to select an idle trunk in the previously determined one of said groups.

12. In a signaling system, an automatic switch of the priinary-secondary motion type including a wiper set having access to an associated terminal bank arranged in levels, first and second groups of trunks terminated in a given level of said bank, mechanism operable between two posif tions respectively corresponding to said rst and second groups of trunks, means for selectively preparing either one of the positions of said mechanism, thereby to determine a corresponding one of said groups of trunks, a tester, means governed when said mechanism occupies a prepared one -of its positions for rendering eiective said tester, means for imparting primary movement to said wiper set to said given level, means for initiating secondary movement of said wiper set in said given level successively to engage the trunks in said iirst and second groups, means responsive to secondary movement of said wiper set in said given level over said irst group of trunks and into engagement with the rst trunk in said second group of trunks for operating said mechanism from one of its positions to the other, whereby said mechanism is operated from a prepared position to an unprepared position or from an unprepared position to a prepared position, said tester being operative when it is renderedr eiiective totest each trunk engaged by said Wiper set, and means controlled by said tester in response to the testing as idle of a trunk engaged by said wiper set for arresting secondary movement of said wiper set, whereby said Wiper set is controlled to select an idle trunk in the previously determined one of said groups.

13. In a signaling system, an automatic switch of the primary-secondary motion type including a wiper set having access to an associated terminal bank arranged in levels, rst and second groups of trunks terminated in a given level of said bank, mechanism operable between two positions respectively corresponding to said first and second groups of trunks, one of the positions of said mechanism being normally prepared, thereby to determine the corresponding one of said groups of trunks, means responsive to a preliminary primary movement of said Wiper set for releasing said wiper set and for preparing the other position of said mechanism, thereby to determine the corresponding other of said groups of trunks, a tester, means governed when said mechanism occupies a prepared one of its positions I or rendering effective said tester, means for imparting primary movement to said wiper set to said given level, means for initiating secondary movement of said wiper set in said given level successively to engage the trunks in said first and second groups, means responsive to secondary movement of said wiper set in said given level over said rst group of trunksand into engagement with the first trunk in said second group of trunks for operating said mechanism from one of its positions to the other, whereby said mechanism is operated from a prepared position to an unprepared position or from an unprepared position to a prepared position, said tester being operative when it is rendered eiective to test each trunk engaged by said wiper set, Vand means controlled by said tester in respouse to the testing as idle of a trunk engaged by said wiper set for arresting secondary movement. of said wiper set, whereby saidwiper set is controlled to select an idle trunk in the previously determined one of said groups.

14. In a signaling system, an automatic switch of the primary-secondary motion type including a wiperset having access to an associated terminal. bank arranged in levels, first and second groups of trunks terminated in a given level of saidbank, mechanism operable between two positions respectively corresponding to said first and second groups of trunks, a tester normally disconnected from said wiper set, thereby to determine said second group of trunks, means responsive to a preliminary primary movement of said vwiper set for releasing said wiper set and for connecting said tester to said wiper set, thereby to determine said first group of trunks, means for imparting primary movement to said wiper set to said given level, means for initiating secondary movement of said wiper -set in said given level successively to engage the trunks in said first and second groups,Y means responsive to secondary movement of said wiper set in said given level over said first group of trunks and into engagement with the rst trunk in said second group of trunks for operating said mechanism from one of its positions to the other, means responsive to the last-mentioned operation of said mechanism for connecting said tester to said wiper set in the event it is disconnected therefrom and for disconnecting said tester from said wiper set in the event it is connected thereto, said tester being operative when it is connected to said wiper set to test each trunk engaged by said wiper set, and means controlled by said tester in response to the testing as idle of a trunk engaged by said wiper set for arresting secondary movement of saidwiper set, whereby said wiper set is controlled to select an idle trunk in the previously determined one of said groups.

15. In a signaling system, an automatic switch of the primary-secondary motion type including a wiper set having access to an associated terminal-bank arranged in levels, first and second groups of trunks terminated in a given level of said bank,-a first Contact set, means for selectively operating said-first Contact set, means for imparting primarymovement to said wiper set to said given level, means for initiating secondary movement of said wiper set in said given level successively to engage the trunks in said first and second groups, a second contact set, means responsive to primary movement of said wiper set to said given level and subsequent secondary movement of said wiper set in said given level over said first group of trunks and into engagement with the first trunk in said second group of trunks Yfor operating said second Contact set, means controlled jointly by said rst and second Contact sets for governing the selectability of the Y 16. In a signaling system, an automatic switch including a shaft mounted for both longitudinal sliding and rotary movements, ,a wiper carried by said shaft, a stationary terminal bank accessible to said wiper and including a plurality of longitudinally spaced-apart rows of terminals arranged in circumferentially spaced-apart relation, a given one of said rows of terminals including rst and second groups of terminals, a cam carried by said shaft, a stationary contact set associated with said cam, and means for imparting longitudinal sliding movement and then rotary movement to said shaft, said cam and said Contact set being so constructed and arranged that said cam is moved adjacent said contact set when said shaft is moved longitudinally tobring said wiper into alignment with said given row of terminals and that said Contact set is operated by said cam when said shaft is rotated to cause said wiper to engage' the Vfirst terminal in said second group.

17. In a signaling system, an automatic switch including a shaft mounted for both longitudinal sliding and rotary movements, a wiper carried by said shaft, a stationary terminal bank accessible to said wiper and including a plurality of longitudinally spaced-apart rows of terminals arranged in circumferentially spaced-apart relation, a cam carried by said shaft, a stationary contact set associated with said cam, and means for imparting longitudinal sliding movement and then rotary movement to said shaft, the longitudinal position of said cam being adjustable with respect to said shaft, whereby said cam is moved adjacentsaid contact set when said shaft is moved longitudinally to bring said wiper into alignment with any predetermined row of terminals in said terminal bank, the rotary position of said cam being adjustable with respect to said shaft, whereby said cam operates said contact set when said shaft is rotated to cause said wiper to engage any predetermined terminal in said predetermined row of terminals in said terminal bank.

18. In a signaling system, an automatic switch including a shaft mounted for both longitudinal sliding and rotary movements, a wiper carried by said shaft, a stationary terminal bank accessible to said wiper and including a plurality of longitudinally spaced-apart rows o-f terminals arranged in circumferentially spaced-apart relation, a cam carried by said shaft, a stationary contact set associated with said cam, means for imparting longitudinal sliding movement and then rotary movement to said shaft, indicia carried by said shaft to facilitate adjustment of the longitudinal position of said cam with respect to said shaft, whereby said cam is moved adjacent said contact set when said shaft is moved longitudinally to bring said wiper into alignment with any predetermined row of terminals in said terminal bank, and indicia carried by said cam to facilitate adjustment of the rotary position thereof with respect to said shaft, whereby said cam operates said contact set when said shaft is rotated to cause said wiper to engage any predetermined terminal in said predetermined row of terminals in said terminal bank.

JOHN ELLIS OSTLINE.

DISCLAIMER 2,315,010.-John Ellis Ostline, Chicago, Ill. SIGNALING SYSTEM. Patent dated March 30, 1943. Disclaimer filed April 6, 1944, by the assignee, Automatic Electric Laboratories, Inc.

Hereby enters this disclaimer to claims 1, 2, and 3 of said Letters Patent.

[Oficial Gazette May 2, 1944.] 

